Regarding Smart Cars and collision safety.
The car is actually pretty safe, believe it or not! The engine is in the back and if you get hit from the rear the engine will move in under the sandwich constructed floor - thus absorbing part of the energy (there are many bigger cars that don´t do that). In the end, if all the energy is not absorbed this way, you have a "safety cage" (see picture) resemble those in rally cars - and this metal profile
wont brake. If you smash into a concrete wall it will be hard - but you will not be crushed.
If you collide with another, heavier, car the entire 800 kg Smart will move - and thus absorbing much of the collission energy.
In the front of the car (where there obviously is no engine) there are a "crash box" (see picture), simply made to absorb enery in a collision (as the motor does in the rear).
Actually, a guy in the swedish Smart Club (that I and two other blokes founded) frontal collided with a Volvo 440 at highway speed (both doing 70-90 kmh) and he got off with two broken legs. My guess would have been that booth drivers died actually... His Smart flew some 15 meters out in a field beside the road - a light but hard car moves instead of beeing crushed!